Periodicitu And Ionisation Energy

Question 1

What is first ionisation energy

Answer 1

The energy needed to remove one mole of outermost electrons from one mole of gaseous atoms of an element to form 1 mole of 1+ ions

Question 2

Why do are consecutive ionisation energies larger

Answer 2

As each election is removed from an atom the remaining ion becomes more positively charged
- nuclear change increases
- stronger nuclear attraction for remaining electrons so more energy is required to remove the outermost electron

Question 3

What is the trend in ionisation energy down a group and why

Answer 3

• ionisation energy decreases
  -nuclear charge increases
  -atomic radius increases
• shielding increases
  -attraction to outermost electron decreases
• ionisation energy decreases as less energy is needed to remove outermost electron

Question 4

What is the trend in ionisation energy across a period

Answer 4

Ionisation energy increases across a period
-nuclear charge increases
- atomic radius decreases
- shielding stays the same/ similar
- attraction to outermost electron increases
-ionisation energy increases as more energy is needed to remove outermost electron

Question 5

Explain why boron’s first ionisation energy is less than Beryllium’s

Answer 5

Be- 1s1 2s2
B- 1s2 2s2 2p1
Outermost electron in B is present in 2p sub shell and in Be a electron is present in 2a sub shell
Electron in subshell of B is in a higher energy subshell hence it will experience more shielding and less nuclear attraction so less energy is required to remove it

Question 6

Why is Ps first ionisation energy higher than Ss

Answer 6

P- 1s2 2s2 2p6 3s2 3p3
S- 1s2 2s2 2p6 3s2 3p4
In both the outermost electron is in the 3p subshell however in s there is 2 electrons in one of the orbitals so there is some repulsion between the paired electrons and which decreases nuclear attraction to the outermost election and reduces energy needed to remove it

Question 7

How does atomic radius change across and down the group

Answer 7

Down the group- nuclear charge increases, shielding increases and attraction to outermost elevation is weaker which increases atomic radius
Across a period- nuclear charge increases, shielding remains the same and attraction to outermost electron increases which decreases atomic radius

Question 8

What are successive ionisation energies

Answer 8

A measure of the energy required to remove each electron in turn for example the second ionisation energy is a measure of how easily a +1 ion loses an electron to form 2+ ions

Question 9

Why is the second ionisation energy of lithium so much larger than the first

Answer 9

A large increase in second ionisation energy indicates the second electron has been removed from a different shell closer to the nucleus with fewer shielding electrons

Question 10

Describe diamond

Answer 10

• giant covalent lattice structure
  4 bonds , tetrahedral structure
  Held together by strong covalent bonds

Properties
-very hard
- very high melting and boiling point as a lot of energy is needed to break covalent bonds
-cannot conduct electricity- no free electors or ions / mobile charge carriers to carry a charge

Question 11

Describe graphite

Answer 11

• giant covalent lattice
• 3 bonds
• strong hexagonal layers (covalent bonds within them)
• weak induced dipole dipole forces between layers

Properties:
Very soft and slippery as layers can slide over each other easily as weak induced dipole dipole bonds break easily

Can conduct as there is a free electron from each carbon , each layer has delocalised electrons which carry charge

Question 12

Describe graphene

Answer 12

3 bonds
Single hexagonal layer with covalent bonds
Stronger than diamond and electrons are able to flow through easily

Question 13

What is covalent bonding

Answer 13

A pair of shared electrons
Atoms are held together due to attraction between positive nuclei and negative electrons
Eg: N2 , O2 , Sicl 4 , Co2

Question 14

Describe simple molecular compounds

Answer 14

Non metal with a non metal
Atoms within molecules are joined together by strong covalent bonds , molecules are bonded together with weak intermolecular forces

Properties:
Low melting and boiling points , the weak forced of attraction between molecules can be broken by a small amount of energy
- soft and brittle
- cannot conduct electricity
Cannot conduct as no free electrons or ions to carry a charge

Question 15

Describe metallic bonding

Answer 15

Metal is held together by the electrostatic attraction between the positive ion and delocalised electrons

Question 16

What does the strength of metallic bonding / metallic lattice depend on

Answer 16

1. The size of ion (ionic radius)
2. Charge of the ion